/*
** $Id: lstate.c,v 2.133 2015/11/13 12:16:51 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/

#define lstate_c
#define LUA_CORE

#include "lprefix.h"


#include <stddef.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "llex.h"
#include "lmem.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"


#if !defined(LUAI_GCPAUSE)
#define LUAI_GCPAUSE    200  /* 200% */
#endif

#if !defined(LUAI_GCMUL)
#define LUAI_GCMUL  200 /* GC runs 'twice the speed' of memory allocation */
#endif


/*
** a macro to help the creation of a unique random seed when a state is
** created; the seed is used to randomize hashes.
*/
#if !defined(luai_makeseed)
#include <time.h>
#define luai_makeseed()     cast(unsigned int, time(NULL))
#endif



/*
** thread state + extra space
*/
typedef struct LX {
    lu_byte extra_[LUA_EXTRASPACE];
    lua_State l;
} LX;


/*
** Main thread combines a thread state and the global state
*/
typedef struct LG {
    LX l;
    global_State g;
} LG;



#define fromstate(L)    (cast(LX *, cast(lu_byte *, (L)) - offsetof(LX, l)))


/*
** Compute an initial seed as random as possible. Rely on Address Space
** Layout Randomization (if present) to increase randomness..
*/
#define addbuff(b,p,e) \
  { size_t t = cast(size_t, e); \
    memcpy(b + p, &t, sizeof(t)); p += sizeof(t); }

static unsigned int makeseed( lua_State* L ) {
    char buff[4 * sizeof( size_t )];
    unsigned int h = luai_makeseed();
    int p = 0;
    addbuff( buff, p, L ); /* heap variable */
    addbuff( buff, p, &h ); /* local variable */
    addbuff( buff, p, luaO_nilobject ); /* global variable */
    addbuff( buff, p, &lua_newstate ); /* public function */
    lua_assert( p == sizeof( buff ) );
    return luaS_hash( buff, p, h );
}


/*
** set GCdebt to a new value keeping the value (totalbytes + GCdebt)
** invariant (and avoiding underflows in 'totalbytes')
*/
void luaE_setdebt( global_State* g, l_mem debt ) {
    l_mem tb = gettotalbytes( g );
    lua_assert( tb > 0 );

    if ( debt < tb - MAX_LMEM ) {
        debt = tb - MAX_LMEM;    /* will make 'totalbytes == MAX_LMEM' */
    }

    g->totalbytes = tb - debt;
    g->GCdebt = debt;
}


CallInfo* luaE_extendCI( lua_State* L ) {
    CallInfo* ci = luaM_new( L, CallInfo );
    lua_assert( L->ci->next == NULL );
    L->ci->next = ci;
    ci->previous = L->ci;
    ci->next = NULL;
    L->nci++;
    return ci;
}


/*
** free all CallInfo structures not in use by a thread
*/
void luaE_freeCI( lua_State* L ) {
    CallInfo* ci = L->ci;
    CallInfo* next = ci->next;
    ci->next = NULL;

    while ( ( ci = next ) != NULL ) {
        next = ci->next;
        luaM_free( L, ci );
        L->nci--;
    }
}


/*
** free half of the CallInfo structures not in use by a thread
*/
void luaE_shrinkCI( lua_State* L ) {
    CallInfo* ci = L->ci;
    CallInfo* next2;  /* next's next */

    /* while there are two nexts */
    while ( ci->next != NULL && ( next2 = ci->next->next ) != NULL ) {
        luaM_free( L, ci->next ); /* free next */
        L->nci--;
        ci->next = next2;  /* remove 'next' from the list */
        next2->previous = ci;
        ci = next2;  /* keep next's next */
    }
}


static void stack_init( lua_State* L1, lua_State* L ) {
    int i;
    CallInfo* ci;
    /* initialize stack array */
    L1->stack = luaM_newvector( L, BASIC_STACK_SIZE, TValue );
    L1->stacksize = BASIC_STACK_SIZE;

    for ( i = 0; i < BASIC_STACK_SIZE; i++ ) {
        setnilvalue( L1->stack + i );    /* erase new stack */
    }

    L1->top = L1->stack;
    L1->stack_last = L1->stack + L1->stacksize - EXTRA_STACK;
    /* initialize first ci */
    ci = &L1->base_ci;
    ci->next = ci->previous = NULL;
    ci->callstatus = 0;
    ci->func = L1->top;
    setnilvalue( L1->top++ ); /* 'function' entry for this 'ci' */
    ci->top = L1->top + LUA_MINSTACK;
    L1->ci = ci;
}


static void freestack( lua_State* L ) {
    if ( L->stack == NULL ) {
        return;    /* stack not completely built yet */
    }

    L->ci = &L->base_ci;  /* free the entire 'ci' list */
    luaE_freeCI( L );
    lua_assert( L->nci == 0 );
    luaM_freearray( L, L->stack, L->stacksize ); /* free stack array */
}


/*
** Create registry table and its predefined values
*/
static void init_registry( lua_State* L, global_State* g ) {
    TValue temp;
    /* create registry */
    Table* registry = luaH_new( L );
    sethvalue( L, &g->l_registry, registry );
    luaH_resize( L, registry, LUA_RIDX_LAST, 0 );
    /* registry[LUA_RIDX_MAINTHREAD] = L */
    setthvalue( L, &temp, L ); /* temp = L */
    luaH_setint( L, registry, LUA_RIDX_MAINTHREAD, &temp );
    /* registry[LUA_RIDX_GLOBALS] = table of globals */
    sethvalue( L, &temp, luaH_new( L ) ); /* temp = new table (global table) */
    luaH_setint( L, registry, LUA_RIDX_GLOBALS, &temp );
}


/*
** open parts of the state that may cause memory-allocation errors.
** ('g->version' != NULL flags that the state was completely build)
*/
static void f_luaopen( lua_State* L, void* ud ) {
    global_State* g = G( L );
    UNUSED( ud );
    stack_init( L, L ); /* init stack */
    init_registry( L, g );
    luaS_init( L );
    luaT_init( L );
    luaX_init( L );
    g->gcrunning = 1;  /* allow gc */
    g->version = lua_version( NULL );
    luai_userstateopen( L );
}


/*
** preinitialize a thread with consistent values without allocating
** any memory (to avoid errors)
*/
static void preinit_thread( lua_State* L, global_State* g ) {
    G( L ) = g;
    L->stack = NULL;
    L->ci = NULL;
    L->nci = 0;
    L->stacksize = 0;
    L->twups = L;  /* thread has no upvalues */
    L->errorJmp = NULL;
    L->nCcalls = 0;
    L->hook = NULL;
    L->hookmask = 0;
    L->basehookcount = 0;
    L->allowhook = 1;
    resethookcount( L );
    L->openupval = NULL;
    L->nny = 1;
    L->status = LUA_OK;
    L->errfunc = 0;
}


static void close_state( lua_State* L ) {
    global_State* g = G( L );
    luaF_close( L, L->stack ); /* close all upvalues for this thread */
    luaC_freeallobjects( L ); /* collect all objects */

    if ( g->version ) { /* closing a fully built state? */
        luai_userstateclose( L );
    }

    luaM_freearray( L, G( L )->strt.hash, G( L )->strt.size );
    freestack( L );
    lua_assert( gettotalbytes( g ) == sizeof( LG ) );
    ( *g->frealloc )( g->ud, fromstate( L ), sizeof( LG ),
                      0 ); /* free main block */
}


LUA_API lua_State* lua_newthread( lua_State* L ) {
    global_State* g = G( L );
    lua_State* L1;
    lua_lock( L );
    luaC_checkGC( L );
    /* create new thread */
    L1 = &cast( LX*, luaM_newobject( L, LUA_TTHREAD, sizeof( LX ) ) )->l;
    L1->marked = luaC_white( g );
    L1->tt = LUA_TTHREAD;
    /* link it on list 'allgc' */
    L1->next = g->allgc;
    g->allgc = obj2gco( L1 );
    /* anchor it on L stack */
    setthvalue( L, L->top, L1 );
    api_incr_top( L );
    preinit_thread( L1, g );
    L1->hookmask = L->hookmask;
    L1->basehookcount = L->basehookcount;
    L1->hook = L->hook;
    resethookcount( L1 );
    /* initialize L1 extra space */
    memcpy( lua_getextraspace( L1 ), lua_getextraspace( g->mainthread ),
            LUA_EXTRASPACE );
    luai_userstatethread( L, L1 );
    stack_init( L1, L ); /* init stack */
    lua_unlock( L );
    return L1;
}


void luaE_freethread( lua_State* L, lua_State* L1 ) {
    LX* l = fromstate( L1 );
    luaF_close( L1, L1->stack ); /* close all upvalues for this thread */
    lua_assert( L1->openupval == NULL );
    luai_userstatefree( L, L1 );
    freestack( L1 );
    luaM_free( L, l );
}


LUA_API lua_State* lua_newstate( lua_Alloc f, void* ud ) {
    int i;
    lua_State* L;
    global_State* g;
    LG* l = cast( LG*, ( *f )( ud, NULL, LUA_TTHREAD, sizeof( LG ) ) );

    if ( l == NULL ) {
        return NULL;
    }

    L = &l->l.l;
    g = &l->g;
    L->next = NULL;
    L->tt = LUA_TTHREAD;
    g->currentwhite = bitmask( WHITE0BIT );
    L->marked = luaC_white( g );
    preinit_thread( L, g );
    g->frealloc = f;
    g->ud = ud;
    g->mainthread = L;
    g->seed = makeseed( L );
    g->gcrunning = 0;  /* no GC while building state */
    g->GCestimate = 0;
    g->strt.size = g->strt.nuse = 0;
    g->strt.hash = NULL;
    setnilvalue( &g->l_registry );
    g->panic = NULL;
    g->version = NULL;
    g->gcstate = GCSpause;
    g->gckind = KGC_NORMAL;
    g->allgc = g->finobj = g->tobefnz = g->fixedgc = NULL;
    g->sweepgc = NULL;
    g->gray = g->grayagain = NULL;
    g->weak = g->ephemeron = g->allweak = NULL;
    g->twups = NULL;
    g->totalbytes = sizeof( LG );
    g->GCdebt = 0;
    g->gcfinnum = 0;
    g->gcpause = LUAI_GCPAUSE;
    g->gcstepmul = LUAI_GCMUL;

    for ( i = 0; i < LUA_NUMTAGS; i++ ) {
        g->mt[i] = NULL;
    }

    if ( luaD_rawrunprotected( L, f_luaopen, NULL ) != LUA_OK ) {
        /* memory allocation error: free partial state */
        close_state( L );
        L = NULL;
    }

    return L;
}


LUA_API void lua_close( lua_State* L ) {
    L = G( L )->mainthread; /* only the main thread can be closed */
    lua_lock( L );
    close_state( L );
}


